Metal dusting

This introductory review paper summarizes shortly the research on metal dusting, conducted in the MPI for Iron Research during the last dozen years. Metal dusting is a disintegration of metals and alloys to a dust of graphite and metal particles, occurring in carburizing atmospheres at a_C > 1 and caused by the tendency to graphite formation. The cause of destruction is inward growth of graphite planes into the metal phase, or in the case of iron and low alloy steels into cementite formed as an intermediate. The kinetics of metal dusting on iron and steels was elucidated concerning dependencies on time, temperature and partial pressures. High alloy steels and Ni‐base alloys are attacked through defects in the oxide scale which leads to pitting and outgrowth of coke protrusions, after initial internal formation of stable carbides M₂₃C₆, M₇C₃ and MC. A dense oxide layer prevents metal dusting, but formation of a protective Cr‐rich scale must be favored by a fine‐grain microstructure and/or surface deformation, providing fast diffusion paths for Cr. Additional protection is possible by sulfur from the atmosphere, since sulfur adsorbs on metal surfaces and suppresses carburization. Sulfur also interrupts the metal dusting mechanism on iron and steels, causing slow cementite growth. Under conditions where no sulfur addition is possible, the use of high Cr Nickelbase‐alloys is recommended, they are largely protected by an oxide scale and if metal dusting takes place, its rate is much slower than on steels.     

浅论企业再就业服务中心的建立

分析了实施再就业管理的基本条件和主要内容以及它在企业经营管理中的作用 ,指出在再就业服务管理中理顺处理好几个重要关系是适应经济发展的需要。     

采用精馏法提高氧化锌产品档次

介绍我国精馏法生产氧化锌的工艺及特点 ,通过与直接法和传统间接法氧化锌生产工艺的比较 ,阐明高纯氧化锌的市场前景 ,并论证了精馏法生产高纯氧化锌是相关企业的发展方向     

部分13层框剪结构楼房的控制爆破拆除

待拆13层钢筋混凝土框剪结构物是病房楼东侧的一部分,东西长11 4m、南北宽18 6m、高45m,剪力墙厚20cm和25cm。采用单向折叠定向倒塌的方案,使结构从南到北逐段微差起爆和解体。文中介绍了爆破切口高度的确定、钻孔爆破参数的选取、爆区的划分、起爆顺序、预处理以及安全防护措施。同时对倒向偏差的原因进行了分析。     

Design aspects of satellite–cellular hybrid wireless systems

In this paper we investigate various issues related to the design of satellite–cellular hybrid systems. First, we review the fundamental problems of channel partitioning and call admission/assignment. Second, we study the impact of different frequency reuse constraints, in both layers, on the optimum channel partitioning. Third, we investigate, analytically and via simulation, the effect of reducing the cell size. We emphasize the blocking‐forced termination probabilities trade‐off for pure cellular and satellite–cellular hybrid systems. Accordingly, an optimization problem with respect to the cell size is formulated. Finally, we search for the optimum dynamic call re‐assignment policy that improves the system capacity at the expense of the complexity associated with tearing down a connection in one system and setting‐up an alternative one in the other system. For a small hybrid system, we characterized the optimum re‐assignment policies that minimize the blocking probability, dropping probability, and a weighted cost function of these probabilities. Copyright © 2002 John Wiley & Sons, Ltd.     

Stabilisation des émulsions: influence des colloïdes hydrophiles

Afin d'améliorer la stabilité des émulsions à base d'huile de paraffine, d'huile d'olive, de Myglyol 812 et de plusieurs couples émulsifiants constitués de tensio-actifs non-ioniques, cinq polymères hydrophiles ont été utilisés: la carboxyméthyl cellulose sodique, l'hydroxyéthyl cellulose, l'agar-agar, une argile hydrophile synthétique et un polymère carboxyvinylique.
Après douze mois de conservation, il ressort un certain nombre de points: parmi les trois huiles utilisées l'émulsion à base d'huile d'olive se révèle être la plus difficile à stabiliser. L'addition d'un hydrocolloïde n'entraîne pas forcément la stabilisation d'une émulsion et parmi les additifs testés c'est le polymère acrylique qui se révèle être le plus efficace.
Stabilisation of emulsions: influence of hydrophilic colloids     

基于全局模型的产品特征造型系统

基于特征的设计在当今ＣＡＤ／ＣＡＭ技术中扮演了十分重要的角色，本文以我们自行开发的面向机械产品设计的参数货物上造型系统ＺＤ－ＭＣＡＤⅡ＾〔１〕为背景，介绍了ＺＤ－ＭＣＡＤⅡ中的全局产品数据模型，给出了特征及其依赖的描述方法，特征依赖以半序网的形式表示，设计特征与制造特征通过特征映射实现统一。文章对于产品模型的建立及特征形成规则与特征重构都作了详细的分析。     

Digital Solipsisim and the Paradox of the Great ‘Forgetting’

Neil Spiller counters the main theme of this issue by questioning the dominant focus on production and new technologies in architectural culture, which places a premium on the generation of ‘ever more gratuitous complex surfaces and structures’. Could this inward-looking emphasis on process and obsessive love of new technologies be at the expense of the final product? Are we in danger of producing artefacts that lose sight of human expression and poetics in the competitive drive for greater complexity? Are we, in fact, heading towards a great ‘forgetting’ in which humanity is subtracted from the architectural product?